Blending apparatus for vaporizing propane

ABSTRACT

An apparatus for providing from a supply of liquefied fuel fluid, such as propane, an aerated, gaseous fuel fluid to be added to a natural gas distribution system from supplementation, standby or peak shaving service. The apparatus includes means for vaporizing a portion of the liquid fuel as a result of absorption of thermal energy developed in the process of compressing ambient air to be mixed with the supply fuel fluid in the aeration thereof. The apparatus further includes means for dehumidifying the compressed air utilizing a flashing of another portion of the liquid fuel into the compressed air so as to cool the air and permit subsequent removal of the condensed moisture by a separator apparatus.

Bivins, Jr.

1451 May 13,1975

[54} BLENDING APPARATUS FOR VAPORIZING 3,724229 4/1973 Seliber 1. 62/52 PROPANE FOREIGN PATENTS OR APPLICATIONS [76] Inventor: Henry W. Bivins. Jr., 5030 680,032 6/1964 Canada 1. 62/52 Brummel, Skokie, Ill. 60076 [22] Filed: Aug. 23, 1973 Primary ExaminerS. Leon Bashore Assistant Exam1nerAlfred D'Andrea, Jr. [2 App 390,835 Attorney, Agent, or Ft'rm-Hofgren, Wegner, Allen,

Stellman & McCord [52] US. Cl 48/180 A; 48/180 R; 48/180 C;

48/180 M; 62/52; 261/160 1 1 ABSTRACT [51] Int. Cl B0lf 3/02 An apparatus for providing from a supply of liquefied [58] F ld f a h 3/ 130 I80 fuel fluid. such as propane, an aerated, gaseous fuel 48/130 I30 A, I96 197 FM, 96 fluid to be added to a natural gas distribution system R; 62/52; 203/25, /372; 261/160 from supplementation, standby or peak shaving service. The apparatus includes means for vaporizing a [56] R feren s Cit! portion of the liquid fuel as a result of absorption of UNITED STATES PATENTS thermal energy developed in the process of compress- 2 221 352 11/1940 Lauder 48/180 R lng ambiem air be mixed with the fuel fluid 2322926 9/1950 Evans y y g V ug [96 R X in the aeration thereof. The apparatus further includes 2,618,935 11/1952 Malir, Jr. 48/190 X means for dehumidifying the compressed air utilizing a 3,266 26I 8/1966 Anderson 62/52 flashing of another portion of the liquid fuel into the 3,421,574 1/1969 Kals v 62/52 X compressed air so as to cool the air and permit subse- 1 4/1969 Sm'lh a A H 62/52 quent removal of the condensed moisture by a separa- 3,479,164 11/1969 Edler I 1 I 1 a t I 48/190 mt apparatus 3,53S885 /1970 Frljlink et al 62/52 X 3 658 499 4/1972 Delahunty .1 48/196 R 17 Claims, 2 Drawing Figures AIR FILTER r ATMOSPHERIC 32 0 'NTAKE MOISTURE m". SEPARATOR 1 37a I \I rRla P Eo ,5 NATgfiL GAS 0U DRIVE l I p. complz'gssoa I 3/ FSS'IE ,6 l 38 wmSE'P To H 22mm. W W L25 I ,1 :5 127 37 .L/ l (8 :1 39 II PROPANE I 4u. .1. I ll /7 '6 REBOILER I :1 1: P1 22a 22 l I u GLYCOL 22b 26'/' l l WATER I I I I: I; PUMP I I I 1 36 I33 1% w, LIQUID I 1 I fikot v nu, I I

l 2 I 35 TEMP.

cbfififoi v 20 1| STORAGE PROPANE TANK VAPORIZER VALVE FOR RATIO CONTROL STEAM OR NATURAL GAS FIRED BLENDING APPARATUS FOR VAPORIZING PROPANE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fluid supply apparatus, and in particular, to apparatus for providing from a supply of liquefied fuel fluid a gaseous fuel fluid.

2. Description of the Prior Art In the distribution of natural gas, variations in demand have required reserve supply means. The reserve supplies have been provided by blenders which are thusly operated mostly in intermittent service and, thus, little consideration has heretofore been given as to maximizing the efficiency thereof. Conventionally, the reserve gas supply has been in the form of a blend of propane and air in a conventional ratio of approximately 53 percent propane and 47 percent air. The propane is conventionally provided in the form of liquefied propane and is provided as a by-product of conventional oil refining.

The suppliers of such liquefied propane have recently begun to require that the natural gas distribution com panies purchase the propane on a continual basis and it has become economically desirable to provide a con tinuous blending of the propane-air mixture with the natural gas.

In the past, the peak requirements for natural gas have been in the coldest winter weather when heating units are operated at maximum level. Under these conditions, the compressed air is relatively low in humidity and presents no moisture problem in the mixing thereof with the propane.

The compression of the air has conventionally been effected by air compressors utilizing natural gas engine drives and again, as these drives are operated primarily in the coldest weather, minimum cooling of the air compressor drives has been required. Further as the ambient air was conventionally of extremely low temperature, no aftercoolers were conventionally provided for cooling the compressed air.

SUMMARY OF THE INVENTION The present invention comprehends an improved apparatus for providing from a supply of liquefied fuel fluid, such as liquid propane, butane, etc., a gaseous fuel fluid suitable for blending into a natural gas distribution supply.

More specifically, the invention comprehends providing such an apparatus wherein a portion of the fuel delivered to the natural gas supply is vaporized as a result of heat exchange with the means for compressing ambient air to be mixed with another portion of the fuel. In the illustrated embodiment, the air compressor is powered by a natural gas engine drive and the liquid fuel is vaporized by heat exchange with a coolant liquid flowed in heat exchange relationship with the engine drive and the liquid fuel.

The compressed air is dehumidified by cooling through a heat transfer surface so as to condense moisture therein. The condensed moisture is separated from the air in a conventional moisture separator apparatus. After the moisture separator, a liquid fuel stream is flashed into the dry air stream to provide the low temperature sink required for the heat exchange service.

A third means for vaporizing the liquid fuel may be provided which may utilize a conventional thermal energy source such as steam or natural gas burners and the vaporized fuel is delivered from each of the differ ent vaporizing means such as the air compressor drive cooling means, the dehumidifying means, and the main vaporizing means to a delivery means defining the connection to the natural gas distribution system.

Resultingly, the vaporized power required may be reduced substantially to zero depending on the ambient air conditions. The use of the liquid fuel vaporizer for cooling the air compressor drive affords a substantial saving in the cost of the apparatus and the operation. The direct injection of liquid fuel into the air system results in a fuel vapor pressure that is compatible to dehumidification of the compressed air without having to pressure boost to the natural gas distribution as would be required by a single phase or indirect means. The portion of the fuel fluid vaporized in the air compressor drive cooling means and the dehumidifying means may be subtracted from the requirements of the main vapor izer so as to further increase the efficiency of the system.

The apparatus of the present invention is extremely simple and economical of construction while yet providing the highly desirable advantages discussed above.

BRIEF DESCRIPTION OF THE DRAWING Other features and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawing wherein:

FIG. I is a schematic flow diagram of an apparatus embodying the invention; and

FIG. 2 is a fragmentary schematic illustration of a modified portion of the apparatus for dehumidifying the compressed air.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment of the invention as dis closed in FIG. 1 of the drawing, an apparatus generally designated 10 is provided for delivering a supply of fuel fluid, such as propane, to a delivery means generally designated 11 comprising a connection to a natural gas distribution system main. The fuel fluid is provided from a supply 12 of liquefied fluid and is converted in the apparatus 10 to a gaseous fuel fluid suitable to be mixed with the natural gas. Illustratively, the gaseous fluid may comprise a blend of approximately 53 percent propane and 47 percent air.

In the illustrated embodiment, air is compressed by a conventional air compressor I3 utilizing ambient air delivered thereto through a suitable conventional filter 14. The compressor may be driven by suitable power means, such as a natural gas engine drive 15, and compressor l3 and drive 15 may be suitably cooled by a recirculating glycol-water system generally designated 16 utilizing a conventional pump 17 for effecting the desired circulation.

Liquid fuel is delivered by a conventional pump 18 from supply 12 through a suitable valve I9 to a vapor izer 20 which may utilize a conventional source of thermal energy such as steam or natural gas-fired means. The vaporized fuel is delivered from vaporizer 20 to the delivery means 11 for mixture with air delivered from the compressor I3. The ratio of the air and fuel is controlled by regulation of valve 19 by means of an orifice control 21 in the air flow path as will be brought out more fully hereinafter.

The heat transfer liquid utilized for cooling the compressor drive and compressor 13 is placed in heat transfer association with a portion of the liquid fuel fluid in a reboiler generally designated 22. The coolant liquid is delivered from air compressor 13 to a first portion 220 of the reboiler. Liquid propane is delivered through a liquid level control valve 23 to a second portion 22b of the reboiler in heat transfer association with the coolant liquid in portion 220. A liquid level control 24 is provided for maintaining the level of liquid propane at level L1 in reboiler portion 22b.

Heat transfer from the coolant liquid in portion 22a causes vaporization of the propane liquid in portion 22b and the vaporized propane is delivered through a conduit 25 to the outlet connection 11. The vaporization of a portion of the liquid fuel delivered to delivery means 11 in cooling the air compressor means reduces the load on vaporizor 20 thereby increasing the effi ciency of apparatus 10 and further permitting the appa ratus to be used over a wide range of ambient temperature conditions. If desired, however, where the compressor drive utilizes an electric motor or the like, the reboiler means may be omitted for minimizing the cost of the apparatus.

The compressed air may include moisture which preferably should be removed before delivery of the air to the delivery means 11. To this end, apparatus 10 includes a dehumidifying means generally designated 26 including a regeneration air chiller 27 comprising a shell and tube heat exchanger including an outer shell 28 and tube 29. Compressed air is delivered through an inlet 30 and is passed through tubes 29 to an outlet 31 connected to a conventional moisture separator 32. The air is cooled to a low temperature, such as approximately 37 F. by flashing propane from a spray nozzle counter flow into conduit 37.

More specifically, a portion of the liquid propane is delivered from valve 19, through a conduit 34 provided with a temperature controlled valve 35, and an inlet connector 36 to chamber 33 and conduit 37. Air is delivered to connector 36 by conduits 37a and 37b connected in series through orifice 21 from moisture separator 32. A portion of the propane vaporizes at connector 36 and conduit 37b and the remainder vaporizes within chamber 33 as a result of the mixture of the propane with the air in accordance with the partial pressure law of fluid pressures. The blending of the air and propane lowers the vapor pressure of the propane to provide an excellent low temperature heat transfer means without requiring that the vapor pressure be subsequently boosted to permit delivery thereof through the delivery means 11 to the natural gas main.

lllustratively, the aerated fuel mixture delivered from the outlet 38 of chamber 33 may have a temperature of approximately 32 F., which temperature may be maintained by means of a control 39 sensing the temperature at outlet 38 and controlling valve 35. The airfuel mixture is delivered to conduit 25 from outlet 38 for delivery with the vaporized propane from reboiler 22 to delivery means 11.

Thus, three separate deliveries of propane gas are effected to delivery means 11 in the illustrated apparatus 10. The vaporization of the propane in the air compressor cooling means and the dehumidifying means effectively reduces the load on the vaporizer 20, thus not only providing the highly desirable improved functioning of the apparatus, but further increasing the efficiency thereof.

Where the temperature of the compressed air delivered through inlet 30 to chamber 33 is approximately F. or less, it has been found advantageous to provide a parallel fluid flow, as shown in the drawing, wherein the air flow through the tubes 29 and the flow of blended fluid through the chamber 33 are in the same direction through the air chiller. As will be obvi ous to those skilled in the art, where a higher temperature compressed air is provided, a 2 pass channel down counterconcurrent flow system, such as illustrated in FIG. 2, may be utilized. As shown in FIG. 2, where a counter-current flow system is utilized both the inlet and outlet 131 may be disposed at the lower end of shell 127. The tubes 129 would comprise conventional return bend tubes having both an inlet and outlet at the lower end of the shell for connection to the inlet 130 and the outlet 131, respectively. Under extreme conditions, a conventional counter-flow system (not shown) may be suitable.

lllustratively, pump 18 may provide the liquid propane at a pressure of approximately 15 to 25 p.s.i.g. above gas main pressure. Similarly, air compressor 13 is preferably arranged to provide compressed air at 5 to l0 p.s.i.g. above gas main pressure at connector 11 to allow for system losses through the equipment. Typically, the gas main pressure is between and p.s.i.g. The vaporized propane from reboiler 22 may have a temperature illustrative of approximately l00 F. for mixture with the lower temperature blended airfuel mixture delivered from the dehumidifying means 26. The coolant system of the air compressor may utilize a 50 percent ethylene glycol and water mixture which may be maintained in the range of approximately 140 to l 15 F. by the heat exchange with the liquid propane in reboiler 22.

The foregoing disclosure of specific embodiments is illustrative of the broad inventive concepts comprehended by the invention.

1 claim:

1. Apparatus for providing from a supply of liquefied fuel fluid a gaseous fuel fluid, comprising: delivery means; powered means for compressing ambient air; means providing a heat transfer coolant in heat exchange relationship with said powered means for cooling said powered means; means for providing heat exchange between the liquid fuel fluid and said coolant for cooling said coolant and vaporizing said liquid fuel fluid; and means for delivering to said delivery means a mixture of fuel fluid vaporized by said heat exchange means and air compressed by said powered means.

2. The apparatus of claim 1 wherein said powered means includes a natural gas engine drive means.

3. The apparatus of claim 1 wherein said heat exchange means includes means providing a liquid heat exchange medium for transferring heat from said air compressing means to said liquid fuel fluid.

4. The apparatus of claim 1 wherein said heat exchange means includes reboiler tank and means for maintaining a level of liquid fuel fluid therein for heat exchange with the air compressing means.

5. The apparatus of claim 1 further including means for removing moisture from the compressed air prior to the delivery thereof to said delivery means.

6. The apparatus of claim 1 further including means for vaporizing a second portion of the liquid fuel fluid and combining the vaporized fuel fluid with the compressed air, said delivery means further defining means for delivering the combined vaporized fuel fluid and compressed air to said delivery means.

7. The apparatus of claim 1 further including means for flashing a second portion of the liquefied fuel fluid into the compressed air to refrigerate the compressed air.

8. The apparatus of claim 1 further including means responsive to a change of condition of a second portion of the liquefied fuel fluid for removing moisture from the compressed air.

9. Apparatus for providing from a supply of liquefied fuel fluid an aerated gaseous fuel fluid, comprising: delivery means; means for providing compressed air; means for flashing the liquefied fuel fluid; means responsive to the flashing of the liquefied fuel fluid for dehumidifying the compressed air; and means for delivering a mixture of the dehumidified compressed air and the flashed fuel fluid to said delivery means.

10. The apparatus of claim 9 wherein said flashing means comprises means for flashing said liquefied fuel fluid into the compressed air, and said dehumidifying means includes means to cool the air suitably to condense moisture therein and means for separating the condensed moisture from the cooled air.

11. THe apparatus of claim 9 wherein the flashing means is arranged to further cool the dehumidified air subsequent to the dehumidification thereof.

12. The apparatus of claim 9 wherein said dehumidifying means comprises means for cooling the air suitably to condense moisture therein, and means for separating condensed moisture from the cooled air, said apparatus further including means for placing the dehumidified air in heat exchange relationship with the flashing liquid fuel fluid for further cooling the dehumidified air prior to delivery to said delivery means.

13. The apparatus of claim 9 wherein said dehumidifying means comprises a shell and tube heat exchanger arranged to cause vaporization of the liquefied fuel fluid into the compressed air within the shell portion thereof and thereby cool compressed air in the tube portion thereof suitably to condense moisture therein, means for separating the condensed moisture from the cooled air, the dehumidified air passing through the shell of the heat exchanger with the vaporizing liquefied fuel fluid further cooling the air prior to the delivery thereof to said delivery means.

14. The apparatus of claim 9 further including controlled valve means responsive to the rate of flow of the dehumidified air for controlling the rate of delivery of liquefied fuel fluid from the supply.

15. The apparatus of claim 14 wherein said controlled valve means includes orifice means in the flow path of the air between said flashing means and said delivery means, and a valve responsive to the flow through the orifice means for controlling the flow of liquefied fuel fluid from the supply.

16. The apparatus of claim 9 wherein said flashing means includes a nozzle for injecting fuel fluid from the supply into the dehumidified compressed air.

17. The apparatus of claim 9 further including means for vaporizing a portion of the liquefied fuel fluid of said supply and means for deliverying said vaporized portion to said delivery means. 

1. APPARATUS FOR PROVIDING FROM A SUPPLY OF LIQUEFIED FUEL FLUID A GASEOUS FUEL FLUID, COMPRISING: DELIVERY MEANS; POWERED MEANS FOR COMPRISING AMBIENT AIR; MEANS PROVIDING A HEAT TRANSFER COOLANT IN HEAT EXHCANGE RELATIONSHIP WITH SAID POWERED MEANS FOR COOLING SAID POWERED MEANS; MEANS FOR PROVIDING HEAT EXCHANGE BETWEEN THE LIQUID FUEL FLUID AND SAID COOLANT FOR COOLING SAID COOLANT AND VAPORIZING SAID LIQUID FUEL FLUID; AND MEANS FOR DELIVERING TO SAID DELIVERY MEANS A MIXTURE OF FUEL FLUID VAPORIZED BY SAID HEAT EXCHANGE MEANS AND AIR COMPRESSED BY SAID POWERED MEANS.
 2. The apparatus of claim 1 wherein said powered means includes a natural gas engine drive means.
 3. The apparatus of claim 1 wherein said heat exchange means includes means providing a liquid heat exchange medium for transferring heat from said air compressing means to said liquid fuel fluid.
 4. The apparatus of claim 1 wherein said heat exchange means includes reboiler tank and means for maintaining a level of liquid fuel fluid therein for heat exchange with the air compressing means.
 5. The apparatus of claim 1 further including means for removing moisture from the compressed air prior to the delivery thereof to said delivery means.
 6. The apparatus of claim 1 further including means for vaporizing a second portion of the liquid fuel fluid and combining the vaporized fuel fluid with the compressed air, said delivery means further defining means for delivering the combined vaporized fuel fluid and compressed air to said delivery means.
 7. The apparatus of claim 1 further including means for flashing a second portion of the liquefied fuel fluid into the compressed air to refrigerate the compressed air.
 8. The apparatus of claim 1 further including means responsive to a change of condition of a second portion of the liquefied fuel fluid for removing moisture from the compressed air.
 9. APPARATUS FOR PROVIDING FROM A SUPPLY OF LIQUEFIED FUEL FLUID AN AERATED GASEOUS FUEL FLUID, COMPRISING: DELIVERY MEANS; MEANS FOR PROVIDING COMPRESSED AIR; MEANS FOR FLASHING THE LIQUEFIED FUEL FLUID; MEANS RESPONSIVE TO THE FLASHING OF THE LIQUEFIED FUEL FLUID FOR DEHUMIDIFYING THE COMPRESSED AIR; AND MEANS FOR DELIVERING A MIXTURE OF THE DEHUMIDIFIED COMPRESSED AIR AND THE FLASHED FUEL FLUID TO SAID DELIVERY MEANS.
 10. The apparatus of claim 9 wherein said flashing means comprises means for flashing said liquefied fuel fluid into the compressed air, and said dehumidifying means includes means to cool the air suitably to condense moisture therein and means for separating the condensed moisture from the cooled air.
 11. THe apparatus of claim 9 wherein the flashing means is arranged to further cool the dehumidified air subsequent to the dehumidification thereof.
 12. The apparatus of claim 9 wherein said dehumidifying means comprises means for cooling the air suitably to condense moisture therein, and means for separating condensed moisture from the cooled air, said apparatus further including means for placing the dehumidified air in heat exchange relationship with the flashing liquid fuel fluid for further cooling the dehumidified air prior to delivery to said delivery means.
 13. The apparatus of claim 9 wherein said dehumidifying means comprises a shell and tube heat exchanger arranged to cause vaporization of the liquefied fuel fluid into the compressed air within the shell portion thereof and thereby cool compressed air in the tube portion thereof suitably to condense moisture therein, means for separating the condensed moisture from the cooled air, the dehumidified air passing through the shell of the heat exchanger with the vaporizing liquefied fuel fluid further cooling the air prior to the delivery thereof to said delivery means.
 14. The apparatus of claim 9 further including controlled valve means responsive to the rate of flow of the dehumidified air for controlling the rate of delivery of liquefied fuel fluid from the supply.
 15. The apparatus of claim 14 wherein said controlled valve means includes orifice means in the flow path of the air between said flashing means and said delivery means, and a valve responsive to the flow through the orifice means for controlling the flow of liquefied fuel fluid from the supply.
 16. The apparatus of claim 9 wherein said flashing means includes a nozzle for injecting fuel fluid from the supply into the dehumidified compressed air.
 17. The apparatus of claim 9 further including means for vaporizing a portion of the liquefied fuel fluid of said supply and means for deliverying said vaporized portion to said delivery means. 